Add support for SRI (Subresource Integrity)

[willdurand]

SRI used to be supported in CRA (#1176) but it was removed because of some incompatibilities (#1231).

Could we re-add SRI support in CRA? I feel like the reasons given in #1231 could be solved.

[kumar303]

Here are some benefits of SRI:

• It protects against CDN takeovers. This is important because CDNs are often third party services with separate credentials, etc.
• It adds defense in depth against DNS hijacking
• It adds defense in depth against malicious (or privacy invasive) browser extensions and / or anti-virus software
• It allows you to use a CDN without https more safely. Today, this is not so important since most CDNs use https.

[stale]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[willdurand]

Well... this issue is rather waiting for constructive comments (not from a bot) :)

[cnorthwood]

I wonder if taking essentially the same approach as the original one in #1176, but with an env var to disable it if it causes issues (similar to INLINE_RUNTIME_CHUNK for those of use using strict CSP configurations that ban unsafe-inline) would be best? or even off by default with an env var to opt in (although imo making security opt-in isn't the best idea)

[stale]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

[willdurand]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 5 days if no further activity occurs.

Nope.